Tractor beam
[3] Several theories that have predicted that repulsive effects do not fall within the category of tractor and repulsor beams because of the absence of field collimation.
[citation needed] A variant of Burkhard Heim's theory by Walter Dröscher, Institut für Grenzgebiete der Wissenschaft (IGW), Innsbruck, Austria, and Jocham Häuser, University of Applied Sciences and CLE GmbH, Salzgitter, Germany, predicted a repulsive force field of gravitophotons could be produced by a ring rotating above a very strong magnetic field.
But the works by Forward, Dröscher, and Häuser could not be considered as a form of repulsor- or tractor-beam because the predicted impulses and field effects were not confined to a well-defined, collimated region.
In 1992, Professor Yevgeny Podkletnov and R. Nieminen, of the Tampere University of Technology, discovered weight fluctuations in objects above an electromagnetically levitated, massive, composite superconducting disk.
[14] Ning Wu of the Institute of High Energy Physics (Beijing), used the quantum gauge theory of gravity he had developed in 2001 to explain Podkletnov's observations.
[citation needed] A team of scientists at the Australian National University (ANU) led by Professor Andrei Rode created a device similar to a tractor beam to move small particles 1.5 meters through the air.
[23] The spiraling intensity distribution in these non-diffracting beams tends to trap illuminated objects and thus helps to overcome the radiation pressure that ordinarily would drive them down the optical axis.
Orbital angular momentum transferred from the solenoid beam's helical wavefronts then drives the trapped objects upstream along the spiral.
[24] In March 2011, Chinese scientists[specify] posited that a specific type of Bessel beam (a special kind of laser that does not diffract at the center) is capable of creating a pull-like effect on a given microscopic particle, forcing it toward the beam-source.
[citation needed] In 2013, scientists at the Institute of Scientific Instruments (ISI) and the University of St Andrews created a tractor beam that pulls objects on a microscopic level.
"[This quote needs a citation] Dr Cizmar said: "Because of the similarities between optical and acoustic particle manipulation we anticipate that this concept will inspire exciting future studies in areas outside the field of photonics.
"[This quote needs a citation] Physicists from ANU built a reversible tractor beam, capable of transporting particles "one fifth of a millimetre in diameter a distance of up to 20 centimetres, around 100 times further than previous experiments."
[30] In the same year, Dr. Horst Punzmann and his team at ANU developed a tractor beam that works on water, which could potentially be used to contain oil spills, control floating objects, or study the formation of rips on beaches.
[33] In 2016, Rice University scientists discovered that Tesla coils can generate force fields able to manipulate matter through a process called teslaphoresis.
[37] Science fiction movies and telecasts normally depict tractor and repulsor beams as audible, narrow rays of visible light covering a small target area.
